At the last general election, the Conservatives said they would amend health and safety rules so employers would have to treat mental health the same way they treat physical health.

Some 50 executives, including Lord Sugar and bosses from Thames Water and Ford of Britain, have written to Theresa May, asking her to prioritise this particular pledge.

The companies behind the letter argue the promised change in the law would help break the stigma of mental illness at work.

Fionuala Bonnar, from Mental Health First Aid England said: “The change in legislation we are calling for will establish a baseline for protecting mental health in the workplace, ensuring no one is left behind.”